Question

Prior to Rails 3, creating a plugin to extend find was relatively easy: basically override the find method itself in ActiveRecord::Base, calling super if needed.

Now that Arel is being used in Rails 3, (specifically I’m using Rails 3.1), how would I go about doing something similar? The problem is that many of the old find methods are deprecated in favor of scopes like where, order, limit, etc. At what point(s) in the Rails source should I try to override the default behavior?

I’m sure it’s going to be a bit more convoluted than this, but the closest thing I can find that seems like it might be appropriate is the construct_finder_arel method in ActiveRecord::Base.

Answer 1

After digging through Rails source, regardless of Arel being used, find_by_sql method is called on whatever model is performing the find. This can be extended via alias_method_chain as follows:

find_by_sql_with_customization(*args)
  results = find_by_sql_without_customization
  # do something with results here
  results
end

alias_method_chain :find_by_sql, :customization